A synchronous motor with superconducting windings, which are coils with superconducting wires wound therearound, can generate a strong magnetic field without the need to use an iron core therein, and can thus provide as large an output as a synchronous motor with no such superconducting windings, even when miniaturized. In order for superconducting windings to maintain its superconducting state, the superconducting wires need to be continuously cooled. For this, a synchronous motor needs to be provided not only with a wiring device for supplying a current to superconducting windings, but also with various devices for cooling the superconducting windings, and requires special design, and manufacturing processes that are based on cryogenic technology.
Since superconducting windings generally generate a direct current (DC) magnetic field, superconducting windings may be used in synchronous motors as field windings, and copper windings may be used as armature windings for generating an alternating current (AC) magnetic field. In a synchronous motor in which tri-phase AC power is supplied to an armature windings, an armature winding is provided as part of a stator for the reason of supplying a current and for other various structural reasons. Accordingly, in a related-art synchronous motor, a superconducting field winding is generally configured as being part of a rotor.
However, in the related-art superconducting synchronous motor, the superconducting field winding is rotated along with the rotor. As a result, not only the structure of an exciter for applying a current to the superconducting field winding, but also the structure of a cooler for constantly cooling the superconducting field winding, may become complicated, thereby making it difficult to properly control the related-art superconducting synchronous motor and causing frequent breakdowns of the related-art superconducting synchronous motor.